// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/public/browser/notification_registrar.h"

#include <stddef.h>

#include <algorithm>

#include "base/logging.h"
#include "content/browser/notification_service_impl.h"

namespace content {

struct NotificationRegistrar::Record {
    bool operator==(const Record& other) const;

    NotificationObserver* observer;
    int type;
    NotificationSource source;
};

bool NotificationRegistrar::Record::operator==(const Record& other) const
{
    return observer == other.observer && type == other.type && source == other.source;
}

NotificationRegistrar::NotificationRegistrar()
{
    // Force the NotificationService to be constructed (if it isn't already).
    // This ensures the NotificationService will be registered on the
    // AtExitManager before any objects which access it via NotificationRegistrar.
    // This in turn means it will be destroyed after these objects, so they will
    // never try to access the NotificationService after it's been destroyed.
    NotificationServiceImpl::current();
    // It is OK to create a NotificationRegistrar instance on one thread and then
    // use it (exclusively) on another, so we detach from the initial thread.
    DetachFromThread();
}

NotificationRegistrar::~NotificationRegistrar()
{
    RemoveAll();
}

void NotificationRegistrar::Add(NotificationObserver* observer,
    int type,
    const NotificationSource& source)
{
    DCHECK(CalledOnValidThread());
    DCHECK(!IsRegistered(observer, type, source)) << "Duplicate registration.";

    Record record = { observer, type, source };
    registered_.push_back(record);

    NotificationServiceImpl::current()->AddObserver(observer, type, source);
}

void NotificationRegistrar::Remove(NotificationObserver* observer,
    int type,
    const NotificationSource& source)
{
    DCHECK(CalledOnValidThread());

    Record record = { observer, type, source };
    RecordVector::iterator found = std::find(
        registered_.begin(), registered_.end(), record);
    DCHECK(found != registered_.end());

    registered_.erase(found);

    // This can be nullptr if our owner outlives the NotificationService, e.g. if
    // our owner is a Singleton.
    NotificationServiceImpl* service = NotificationServiceImpl::current();
    if (service)
        service->RemoveObserver(observer, type, source);
}

void NotificationRegistrar::RemoveAll()
{
    CHECK(CalledOnValidThread());
    // Early-exit if no registrations, to avoid calling
    // NotificationService::current.  If we've constructed an object with a
    // NotificationRegistrar member, but haven't actually used the notification
    // service, and we reach prgram exit, then calling current() below could try
    // to initialize the service's lazy TLS pointer during exit, which throws
    // wrenches at things.
    if (registered_.empty())
        return;

    // This can be nullptr if our owner outlives the NotificationService, e.g. if
    // our owner is a Singleton.
    NotificationServiceImpl* service = NotificationServiceImpl::current();
    if (service) {
        for (size_t i = 0; i < registered_.size(); i++) {
            service->RemoveObserver(registered_[i].observer,
                registered_[i].type,
                registered_[i].source);
        }
    }
    registered_.clear();
}

bool NotificationRegistrar::IsEmpty() const
{
    DCHECK(CalledOnValidThread());
    return registered_.empty();
}

bool NotificationRegistrar::IsRegistered(NotificationObserver* observer,
    int type,
    const NotificationSource& source)
{
    DCHECK(CalledOnValidThread());
    Record record = { observer, type, source };
    return std::find(registered_.begin(), registered_.end(), record) != registered_.end();
}

} // namespace content
